The common-rail system has been applied for a long time in the fuel injection system of engines. The structure of the common rail for fuel injection is greatly constrained because it needs to withstand a very high pressure. Since a cylindrical structure can withstand a higher pressure than other structures, the cylindrical structure is adopted for almost all existing common rails for fuel injection.
As the standards for exhaust emission in countries all over the world are increasingly becoming more strict, higher requirements are put forward for the urea injection system used for exhaust treatment. How to control the pressure in the urea injection system is a common technical problem in the industry.
In addition, for exhaust treatment of a high-power engine, the pipeline of the urea injection system is often very long and the pressure loss is relatively great, and therefore it is necessary to provide a common rail which can stabilize the system pressure, the application of the common rail, and a urea injection system having the common rail.
In addition, when a common rail is applied in the post-treatment system of a high-power engine, it is often necessary to design another common rail matching it to meet different design requirements. Such a solution greatly increases the cost.
Therefore, it is necessary to design a new common-rail assembly based on the combination of a plurality of common rails to solve the above-mentioned problem.